A tire pressure detector is designed for connecting to a tire valve on a tire of a car for detecting tire pressure, so that a user can timely obtain information about the tire pressure to drive the car safely.
FIG. 1 is an assembled sectional view of a conventional tire pressure detector, which includes a base 91 having a first end screwed to an outer side of a tire valve, and a mating cover 92 screwed to an outer side of an opposite second end of the base 91 through engagement of external threads 93 on the second end of the base 91 with internal threads 94 of the cover 92. An airtight seal ring 95 is disposed between the base 91 and the mating cover 92 at the screwed portion, so that the base 91 and the cover 92 screwed to each other together define an airtight space 96 in and between them. All the necessary components of the tire pressure detector, such as a pressure detecting unit for detecting tire pressure, a signal transmitting unit for sending out a signal indicating the detected tire pressure, and a battery for supplying electric power to the pressure detecting unit, are received in the airtight space 96. Moreover, a valve control assembly 97 is fitted in the first end of the base 91 to locate between the base 91 and the tire valve. The valve control assembly 97 is in contact with the tire valve to thereby normally open the tire valve, allowing air in the tire to flow through the tire valve and the valve control assembly 97 into the airtight space 96, so that the pressure detecting unit in the airtight space 96 can detect the tire pressure from the air flowed into the airtight space 96.
In the above-structured conventional tire pressure detector, the cover 92 is connected to the base 91 through engagement of the internal threads 93 of the cover 92 with the external threads 94 of the base 91. There is not any limiting element provided outside the cover 92. When the cover 92 deforms due to an external force applied thereto or changes in ambient temperature, a peripheral wall of the cover 92 tends to expand and deform because it is not limited by any means. The deformed cover 92 could not air-tightly connect to the base 91 and gaps will exist between the cover 92 and the base 91. Air flowed from the tire into the airtight space 96 tends to continuously leak out via these gaps, which forms a threat to the safety in driving the car.
Moreover, the whole tire pressure detector and the tire valve are located outside the tire to expose to external environment. When the tire is impacted by an external force while the car is driving or is parked, the cover 92 of the tire pressure detector is apt to loosen and finally separate from the base 91. In the conventional tire pressure detector, the valve control assembly 97 is mounted on the base 91 to locate between the base 91 and the tire valve. In the case the base 91 of the tire pressure detector is still screwed to the tire valve while the cover 92 has separated from the base 91, the valve control assembly 97 mounted on the base 91 will keep contacting with the tire valve to push the latter open. Under this situation, air in the tire will continuously flow through the tire valve and the valve control assembly 97 into an open space to cause a leaky tire, which is highly dangerous to a car in moving.
Therefore, the conventional tire pressure detector has low applicability and requires improvement.